Main variables affecting the lactic acid fermentation of table olives

Among the olive varieties, Manzanilla is the most employed as table olives worldwide. Inoculation of the brines of Manzanilla and Gordal olives, which were not treated with alkali, with a strain of Lactobacillus pentosus was carried out and results indicated that variety is one of the main factors to be considered when fermenting olives, even more important than the salt level. This conclusion was based on the presence of a high concentration of antimicrobial compounds, namely the dialdehydic form of decarboxymethyl elenolic acid, either free or linked to hydroxytyrosol in the brines of the Manzanilla variety, as compared to the low level of these substances in the Gordal brines. Likewise, it was also observed that the inhibitory activity of Manzanilla olives against lactic acid bacteria could be counteracted by the addition of nitrogenous supplements such as MRS and yeast extract to their brines. Results obtained from this work are of great interest for the table olive industry in order to develop lactic acid fermentation in olives non‐treated with alkali.     

Effect of different packing treatments on the microbiological and physicochemical characteristics of untreated green olives of the Conservolea cultivar

Microbiological, physicochemical and organoleptic changes were studied in non‐pasteurised samples of untreated green olives cv Conservolea stored at 20 °C for 180 days under different preservation treatments (acidified brine and modified atmospheres). The microbial flora consisted of lactic acid bacteria and yeasts, while no enterobacteria and pseudomonads were enumerated in any package. Although no thermal treatment was applied to the packages, no sediment formation was observed due to the growth of propionic bacteria. Olives packed in brine supplemented with 0.3% lactic and 0.3% citric acids presented the highest acidity, the lowest brine and flesh pH and the lowest dark brine colour as measured by the parameter A₄₄₀?A₇₀₀. Olives packed in modified atmospheres (vacuum, 40% CO₂/30% O₂/30% N₂ and air) presented a progressive loss of fruit firmness and colour with time. At the end of the storage period, olives packed in aerobic conditions and 40% CO₂/30% O₂/30% N₂ presented the lowest firmness and skin colour and were unacceptable to the panellists. The best quality characteristics were maintained in vacuum‐packed olives, as indicated by the higher organoleptic scores. Firmness degradation followed first‐order kinetics (r² > 0.980) and the expected shelf‐life was 23, 15 and 9 months for olives packed in vacuum, 40% CO₂/30% O₂/30% N₂ and air respectively. Copyright © 2004 Society of Chemical Industry     

Production of fermentable media from vine‐trimming wastes and bioconversion into lactic acid by Lactobacillus pentosus

Trimmings of vineshoots, an agricultural waste with little use, were hydrolysed with dilute sulphuric acid (1–5%) in order to obtain sugar solutions suitable as fermentation media. The operational conditions for hydrolysis were selected on the basis of both the generation of hemicellulosic sugars (mainly xylose) and glucose and the concentrations of reaction byproducts affecting fermentation (furfural, hydroxymethylfurfural and acetic acid). Hemicellulosic hydrolysates were supplemented with nutrients and fermented with Lactobacillus pentosus, without any previous detoxification stage, to produce lactic acid. Under the best operational conditions assayed (3% H₂SO₄ and 15 min), 21.8 g lactic acid l^?1 was produced (Q_P = 0.844 g l^?1 h^?1, Y_P/S = 0.77 g g^?1), which represents a theoretical yield of 99.6%. Acetic acid was the primary byproduct formed from xylose, at about 25% of the lactic acid level. Copyright © 2004 Society of Chemical Industry     

高效转化木聚糖为乳酸植物乳杆菌L3的诱变选育及发酵条件的优化

以植物乳杆菌(Lactobacillus.pentosus)L3为出发菌株,进行紫外线和硫酸二乙酯(DES)诱变处理以提高其转化木聚糖生产乳酸的能力。经紫外线和DES诱变处理,得到突变菌株L.pentosusL35-6,其乳酸产量为71.2g/L,比诱变前提高了58.2%。并对其生长及乳酸发酵的条件进行了优化:最适温度为40℃,pH6.5,转速60r/min振荡培养发酵72h效果最好。     

戊糖乳杆菌的鉴定及其发酵D-乳酸的研究

分离得到1株乳酸杆菌LCA,根据其形态、生理生化性质和16S rDNA分子生物技术鉴定,被鉴定为戊糖乳杆菌（Lactobacillus pentosus）,其发酵产物经手性柱高效液相色谱法测定,含有光学纯度为80%以上的D-乳酸,并能利用D-木糖产生D-乳酸。筛选合适的D-乳酸生产菌株和研究D-乳酸的发酵技术对拓宽D-乳酸的应用范围具有重要意义。      

Enhanced lactic acid fermentation of silage by the addition of green tea waste

The effects of green tea waste (GTW) addition on the ensiling of forage were investigated. Wet and dried GTW added at 10, 50, 100 and 200 g kg^?1 of fresh matter (FM) and at 2, 10 and 20 g kg^?1 FM, respectively, decreased pH and increased lactic acid concentration of the silages, whereas the butyric acid concentration and ammonia nitrogen content, as a proportion of a total nitrogen, were lowered, compared with silage without additives (control). To investigate the effect of GTW‐associated LAB on silage fermentation, wet GTW was sterilized by autoclaving or gamma irradiation and added at 50 g kg^?1 FM. The silages made with sterilized GTW showed higher lactic acid concentrations, and lower pH and butyric acid concentrations than controls. The counts of lactic acid bacteria (LAB) were higher in silages made with sterilized GTW than control until 10 days after ensiling. The enhanced lactic acid fermentation was not found when green tea polyphenols (GTP) were added. These data suggested that GTW could enhance LAB growth and lactic acid production of silage, particularly when added at 50 g kg^?1 FM in a wet form or at the equivalent in a dry form. Although neither GTW‐associated LAB nor GTP accounted for the enhancement of lactic acid fermentation, GTW would possibly supply some nutrients which are heat‐stable and effective for LAB growth during silage fermentation. Copyright © 2004 Society of Chemical Industry     

产细菌素戊糖乳杆菌B8发酵动力学模型的建立

从四川香肠中选育出一株具有产细菌素能力的戊糖乳杆菌B8,在10 L发酵罐内对其进行分批发酵动力学研究,建立菌体生长、产物合成、底物消耗及pH随时间变化的动力学模型,确定模型参数,得到其菌体生长动力学模型■ =0.56691-■、细菌素生产动力学模型■=75.25■ +122.94X、葡萄糖消耗动力学模型-■=5.843■+0.799 8X。pH值变化的数学模型y =■+5.992 8。结果表明,模型预测值与实验值吻合较好,为工业放大生产细菌素提供了理论依据和方法。     

Changes in volatile compounds and related biochemical profile during controlled fermentation of cv. Conservolea green olives

The effect of controlled fermentation processes on the profile of volatile and other biochemical compounds of cv. Conservolea green olives processed by the Spanish method was studied. The different treatments included: (a) inoculation with a commercial starter culture of Lactobacillus pentosus, (b) inoculation with a wild strain of Lactobacillus plantarum isolated from a previous fermentation, (c) uninoculated spontaneous process (control). Microbial growth, pH, titratable acidity, reducing sugars, organic acids and volatile compounds were monitored. Starter cultures were effective in establishing an accelerated fermentation process. Both were able to reduce the survival period of Enterobacteria by 7 days, minimizing thus the likelihood of spoilage. Higher acidification of the brines and faster pH drop was observed in inoculated processes, with L. pentosus presenting better performance than the wild strain of L. plantarum. Lactic and acetic were the major organic acids detected by HPLC, the concentration of which increased in the course of fermentation. Citric and malic acids were also present in the brines but they were degraded completely within the first 2 weeks of fermentation. Ethanol, methanol, acetaldehyde, ethyl acetate, isobutyric acid were the major volatile compounds identified by GC. Their concentration varied greatly among the fermentation processes, reflecting varying degrees of microbial activity in the brines.     

香芋乳酸发酵风味的初步研究

对乳酸菌发酵香芋汁工艺进行了初步探讨,通过正交实验得出发酵的最佳工艺条件:保加利亚乳杆菌与嗜热链球菌最佳添加比例为1∶1、发酵温度为42℃、发酵时间为36h、添加蔗糖量5%,该工艺条件下的饮料口味最佳。     

Microbiological and biochemical profile of cv. Conservolea naturally black olives during controlled fermentation with selected strains of lactic acid bacteria

The effect of controlled fermentation processes on the microbial association and biochemical profile of cv. Conservolea naturally black olives processed by the traditional anaerobic method was studied. The different treatments included (a) inoculation with a commercial starter culture of Lactobacillus pentosus, (b) inoculation with a strain of Lactobacillus plantarum isolated from a fermented cassava product and (c) uninoculated spontaneous process. Microbial growth, pH, titratable acidity, organic acids and volatile compounds were monitored throughout the fermentation. The initial microbiota consisted of Gram-negative bacteria, lactic acid bacteria and yeasts. Inhibition of Gram-negative bacteria was evident in all processes. Both starter cultures were effective in establishing an accelerated fermentation process and reduced the survival period of Gram-negative bacteria by 5 days compared with the spontaneous process, minimizing thus the likelihood of spoilage. Higher acidification of the brines was observed in inoculated processes without any significant difference between the two selected starter cultures (113.5 and 117.6mM for L. plantarum and L. pentosus, respectively). L. pentosus was also determined as the major species present during the whole process of spontaneous olive fermentation. It is characteristic that lactic acid fermentation was also initiated rapidly in the spontaneous process, as the conditions of fermentation, mainly the low salt level (6%, w/v) favored the dominance of lactic acid bacteria over yeasts. Lactic, acetic and propionic were the organic acids detected by HPLC in considerable amounts, whereas citric and malic acids were also present at low levels and degraded completely during the processes. Ethanol, methanol, acetaldehyde, ethyl acetate were the major volatile compounds identified by GC. Their concentrations varied among the different treatments, reflecting varying degrees of microbial activity in the brines. The results obtained from this study could help the Greek table olive industry to improve the existing processing schemes in order to increase product consistency and quality expanding the international market for naturally black olives.     

戊糖乳杆菌S1-4产抑菌物质发酵条件的优化及其抑菌谱

通过单因素及正交试验对戊糖乳杆菌S1-4产抑菌物质的发酵条件进行了优化,并其对敏感菌株的抑菌效果进行了探讨。结果表明,戊糖乳杆菌S1-4产抑菌物质的最佳培养条件为：接种量2.0%,培养基初始pH 5.5,32 ℃培养26 h,其抑菌圈平均直径可达（30.08±0.69） mm,优化前其抑菌圈平均直径为（24.41±0.25）mm,优化后抑菌活性提高了0.23 倍。菌株S1-4所产抑菌物质对所试12 种G＋和G－致病菌的生长都起到抑制作用,呈现出较广谱的抑菌特性。因此,菌株S1-4具有可作为食品生物防腐剂的潜在应用价值。     

Effect of potassium sorbate and sodium benzoate on microbial population and fermentation of black olives

Black olive fermentation characteristics and diffusion of preservatives into olives were evaluated in brines containing 500 ppm potassium sorbate, 1000 ppm sodium benzoate, 500 ppm sodium benzoate + 250 ppm potassium sorbate and no preservative (control). Changes in brine pH, acidity and microbial population (lactic acid bacteria, yeasts, moulds) were followed during fermentation and storage. Results indicated that K‐sorbate when used at 500 ppm concentration in black olive fermentation had a slight stimulatory effect on the growth of lactic acid bacteria. The yeast counts of brines containing 500 ppm K‐sorbate and 1000 ppm Na‐benzoate were lower than for the brine containing 250 ppm K‐sorbate + 500 ppm Na‐benzoate and for the control with no preservative, while mould growth was completely inhibited in all treatments during fermentation. Mould counts stayed below the detection limit (<10 cfu g⁻¹) during 214 days of vacuum‐packaged storage. Yeast counts showed a progressive decline within 28 days of storage and then stayed relatively constant in all treatments thereafter. The level of yeast population was higher in the control sample than in the sample containing both preservatives during storage. The diffusion of Na‐benzoate and K‐sorbate into the olives after equilibrium was 64% and 80% during fermentation respectively. © 1999 Society of Chemical Industry     

Microbiological and physicochemical characterisation of green table olives of Halkidiki and Conservolea varieties processed by the Spanish method on industrial scale

The microbiological and physicochemical changes of industrially fermented Halkidiki and Conservolea green table olives were determined. Samples were analysed to monitor the population of lactic acid bacteria (LAB), yeasts and Enterobacteriaceae, together with changes in pH, acidity, salinity, colour, lactic acid, acetic acid and ethanol. LAB and yeast species diversity was evaluated at the beginning (1 day), middle (75 days) and final (135 days) stages of fermentation by RAPD-PCR genomic fingerprinting. Results revealed vigorous lactic acid processes as indicated by the dominance of LAB over yeasts. No Enterobacteriaceae could be detected after 30 days. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) dominated in the beginning of fermentation in both varieties. In the end, Lactiplantibacillus pentosus (formerly Lactobacillus pentosus) and Pediococcus ethanolidurans prevailed in Halkidiki and Conservolea varieties, respectively. As for yeasts, Kluyveromyces lactis/marxianus and Pichia manshurica prevailed at the onset of fermentation in Halkidiki and Conservolea varieties, whereas in the end Pichia membranifaciens dominated in both varieties.     

直接乳酸发酵工艺研究进展

对以淀粉质为原料进行直接乳酸发酵的国内外研究现状进行了综述.介绍了利用米根霉等真菌和解淀粉乳酸细菌进行直接乳酸发酵.以及通过添加降解酶进行同步糖化发酵的三种直接乳酸发酵工艺.指出通过筛选和构建更加高效的具有解淀粉活性的乳酸细菌和真菌,同时通过获得耐受更高温度的乳酸菌来提高同步糖化发酵的温度,进而使直接乳酸发酵工艺更加高效.     

Effect of simulated acidic and salty fermentation conditions on kinetic growth parameters and probiotic potential of Lactobacillus acidipiscis and Lactobacillus pentosus

The technological stress during food processing may alter the beneficial interactions of food-associated Lactobacillus on the host. The effect of initial combined acidic (pH 5.0) and osmotic stress (NaCl 5 %, w/v with or without CaCl₂ 0.02 %, w/v) typically present in vegetable fermentations and cheesemaking were investigated. The growth kinetics prediction, hydrophobicity, auto-aggregation, in vitro survival and adhesion were determined in Lactobacillus acidipiscis and Lactobacillus pentosus isolated from a Mexican salty cheese. The growth was modelled with the modified Gompertz equation (R > 0.99; RMSE < 0.01). The lag phase increased (>10 h), and auto-aggregation was reduced. Hydrophobicity and S-layer total proteins varied. Gut survival reduced >4 log 10 units compared to the initial intake. Nevertheless, adhesion remained the same. Hence, combined stress affected the technological and physiological properties of both strains negatively. Further research is needed to identify the effect of the combined stress on the potential bioactivity of the strains.     

戊糖乳杆菌S1-4所产抑菌物质的生物学特性研究

以内蒙古东部地区酸菜中分离得到的具有产抑菌活性的戊糖乳杆菌S1-4为供试菌,以大肠杆菌（Escherichia coli）3301为指示菌,采用双层琼脂扩散法对其所产抑菌物质的生物学特性进行研究。结果表明,戊糖乳杆菌S1-4所产的抑菌物经木瓜蛋白酶处理后,其抑菌活性明显降低,但对胃蛋白酶和胰蛋白酶不敏感。该抑菌物质经热处理后,对大肠杆菌仍保持较强的抑菌活性,在p H3.5⁵.5条件下,其抑菌活性较稳定。该菌株的发酵上清液分别经部分化学试剂和紫外线照射处理后,仍保持较好的抑菌活性。      

乳酸菌发酵柿汁的制备工艺

介绍了以柿子汁为原料制备乳酸菌发酵饮料的工艺流程,并对原材料和发酵产品的一些营养指标进行了测量。实验表明,乳酸菌发酵的最佳条件是发酵温度30℃、接种量6%、菌种AS1.1482∶6038=2∶1。产品既保留了部分柿子汁的原有风味,又具有乳酸发酵形成的特殊风味,营养价值较高,有一定的保健作用。     

红景天和轮叶党参混合提取物戊糖乳杆菌发酵条件及抗氧化作用分析

目的：优化红景天和轮叶党参混合提取物（mixed extracts from Rhodiola sachalinensis and Codonopsis lanceolata,RCME）戊糖乳杆菌发酵条件,分析发酵产物的主要活性成分组成与含量,评价其抗氧化作用。方法：RCME中接种戊糖乳杆菌,以发酵液中的pH值、总酸含量及生物量为指标,研究发酵所需的最佳时间、培养基组成（红景天和轮叶党参混合比例）、RCME最佳质量浓度;采用比色法测定RCME发酵前后的总蛋白质、中性糖、酸性多糖及总酚含量变化,采用高效液相色谱法分析RCME发酵前后的红景天苷和酪醇含量变化,采用1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基和2,2’-联氮-二（3-乙基-苯并噻唑-6-磺酸）二铵盐自由基（2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt radical,ABTS＋·）清除实验评价RCME发酵物的抗氧化作用。结果：单纯红景天提取物发酵24～72?h,其pH值和总酸含量无明显变化,随着发酵时间延长,乳杆菌数明显减少（P＜0.01）。红景天和轮叶党参混合质量比达到3∶2,发酵24h后发酵液的pH值下降幅度和总酸含量升高的幅度最大,发酵48?h时后,pH值和总酸含量无明显的变化,乳杆菌数有所减少。可溶性固形物质量分数在1.0%～3.0%范围内,红景天苷转化为酪醇的转化率无明显差异。RCME发酵24?h后,红景天苷含量显著减少（P＜0.01）,酸性多糖、总酚、蛋白质及酪醇含量均显著增加（P＜0.05或P＜0.01）。RCME发酵后DPPH自由基和ABTS＋·清除能力明显增强。结论：RCME发酵条件为红景天-轮叶党参混合比例3∶2、可溶性固形物质量分数1.0%～3.0%、发酵时间24?h。